Ok boys and girls, I'm working on a 47 1.5 ton with a single speed rear end, I have a chance to get some Alcoa wheels for the wide 5 lug pattern, but I need to know what gear ratio do I have. It's the stock rear end, any help would be cool.

 

The Green Books lists 5.14, 5.83, and 6.67 ratio options. Have you looked for a tag on the axle? Some axles have a tag with the ring and pinion tooth count numbers on it. Otherwise you get to jack up one side, spin the wheel two revolutions, and count how many times your drive shaft goes around.

 

Ok thanks, looks like I have 6.67 gears, I'm looking to run a turbo 400, are those gears going to make my engine run at to high of rmp at 65 mph ?

 

What engine in front of the automatic three speed?

 

Yes, the engine will be running a pretty high RPM with that gear rear end. The Turbo 400 is direct 1:1 in 3rd gear just like the 4 speed behind the flathead. Even if you ran a 38" tire you would be turning close to 4000 RPM going 65.

 

Thanks for the help Fred & Chris, that's what I needed to know looks like I'll be looking for a modern rear end with some better gearing, planing on driving the truck to work, thanks agian.

 

Maybe Chris can calculate what you'll run with a 5.14 ratio. My 8.25-20s are right about 38" tall. These trucks will beat you up. I have had mine finished for a year and only done the 24 mile round trip to town a dozen times. I do love using it around the place and the two mile trips to friend's houses and shops. Mine has a 2 speed rear end. Low and lower......

 

A couple of thoughts. You could run a 700R4 O/D tranny instead of the turbo 400. Another option would be a rear end out of a mid '70's or so Dodge motorhome M400 chassis. The frame width is the same as your truck and it will have the same 5 on 8" wheel bolt pattern. The one I had for my '40
1 1/2 ton was a 4:56 ratio. One final thought would be an auxiliary trans. My '40 had a Watson 3 speed (low, direct, and O/D) but it still beat me up driving it around town. JMO

 

A 700R4 has an OD of around .70. So with the same setup (38" tire, 6.67 rear and 65 MPH) you would be running 2700 RPM which is much more comfortable and around 2300 at 55.

My advice would be though to just swap the rear to a more friendly ratio where parts are more readily available.

 

Or set the cab on a motorhome chassis. I know the word 'set' makes it sound easy and we all know it isn't. But having just seen Mad Max Fury Road, anything is possible. And then you'd have ps and pb etc, etc.....

 

An axle swap is easy if thats all you want to do. But with swapping the body onto a modern frame it would definitely make it easy to get all the nice things like PS and PB.

And I think the old mad max movies definitely set me on the path to getting my hands into old trucks more than anything else. I thoroughly enjoyed the new film just because of the vehicles.

 

Yea I've gone that route before, putting sheet metal on a modern frame, I didn't like all the fabricating I had to do to make everything fit, with all the bolt on kits out there makes it easy to put disc brakes on the straight axel, and mount a power steering box on ang go.

 

I could be wrong but I believe all the disc brake kits are for 1/2 tons. The
1 1/2 ton front ends are completely different. But if I remember correctly mid '80's 3/4 and 1 ton disc brake assemblies can be adapted to the 1 1/2 ton front axle but now you have 8 lugs instead of the 5 on 8" pattern. IMO stay with the stock front brakes. They will be more than adequate for everyday use.